1. Technical Field
The present invention relates to a safety-enhancing hood stop for a vehicle, which hood stop is arranged to collapse in order to absorb impact energy if the hood is struck by an object such as a pedestrian or cyclist.
2. Background Art
In the event of a collision between a pedestrian or a cyclist and a motor vehicle it is desirable to minimize the extent of injuries incurred, in particular in the chest and head area of the person. It is generally well-known to provide a relatively large minimum distance between a front hood and a rigid sub-structure of the vehicle (vehicle body or frame, various power train components, suspension strut mountings, etc.) so that a sufficient deformation distance is available for the front hood, in order to retard the impact of the pedestrian or cyclist in a biomechanically compatible manner.
With some vehicles the desired minimum distance between a closed front hood and the rigid sub-structure is not available for reasons of packaging, that is, the design of the body, engine, and the hood leaves less than the desired distance between the two components. In such cases, the front hood can be actively raised to achieve the desired deformation distance when a collision between the vehicle and a pedestrian or cyclist is detected or predicted. However, such systems are relatively complex and require accurate detection or prediction of an impending collision to ensure correct activation of the system.
In addition to providing impact protection, hood stop buffers are frequently arranged at the front of the hood to define a closing position of the hood.
EP 1,488,987 A1 shows an example of a hood stop for a front hood, which functions as a conventional stop buffer up to a predefined load. When subjected to a load above the predefined maximum load, as in the case of the impact of a pedestrian or a cyclist on the front hood, the hood stop will undergo plastic deformation in the vertical direction as a supporting first member breaks. The hood stop comprises a deformable second member that absorbs energy during plastic deformation, in order to retard the impact of the pedestrian or cyclist in biomechanically compatible way. A problem with this arrangement is that once the first member has broken or sheared, the hood stop will continue to deform under a relatively low load over the remaining deformation distance. There is no way of controlling the rate at which the second member is deformed once the load on the first member has exceeded the maximum load. Under a relatively high load, the impact may not be completely absorbed before the hood reaches the underlying structure.